Javascript Return Result of jQuery getJSON

Question

The Problem

I am trying to return the result of jQuery's getJSON method.

What I've Tried

I under stand that the getJSON method is asynchronous, and that I cannot simply return the result as you can with synchronous code.

I've looked at other posts and I tried messing around with promises, as well as callbacks, etc... but have gotten nowhere.

My Code (Before Trying Promises, Callbacks, Etc...)

function getCart() {
  jQuery.getJSON("/cart.js").done(function (cart) {
      return cart;
  });
}

cart = getCart();
console.log(cart);

Any direction would be greatly appreciated!